billon

American  

[bil-uhn] / ˈbɪl ən /

noun

1. an alloy used in coinage, consisting of gold or silver with a larger amount of base metal.

2. an alloy of silver with copper or the like, used for coins of small denomination.

3. any coin struck from such an alloy.

---

billon British  

/ ˈbɪlən /

noun

1. an alloy consisting of gold or silver and a base metal, usually copper, used esp for coinage

2. any coin made of such an alloy

---

Etymology

Origin of billon

1720–30; < French: debased metal, originally ingot, equivalent to Middle French bille log ( see billet ²) + -on noun suffix